Photons in and out of Glass
Most recent answer: 08/01/2016
- Tim Harvey (age 56)
Since the frequency f doesn't change as the light goes in or out of the glass, the energy quantum hf doesn't change. Outside the glass the energy is pure photon energy, i.e. electromagnetic in a classical picture. Inside the glass the energy is partly in the form of electrons being partly in higher energy states than they were without the light. (I'm not sure that this adds much to what you were already told.)
What happens to the momentum is a little more interesting. We've got an old answer that deals with this issue somewhat: https://van.physics.illinois.edu/qa/listing.php?id=14665.
Whether the wave is expressed as a quantum wave or a classical, it spreads out over a huge range of angles. It's actually typically much broader than a cone. You can google "dipole radiation pattern" to get some images. So yes, this sort of wave picture is needed to explain two-slit interference. The photons are not little dots following trajectories.
(published on 08/01/2016)